The spectral identity of foveal cones is preserved in hue perception

Abstract

Organisms are faced with the challenge of making inferences about the physical world from incomplete incoming sensory information. One strategy to combat ambiguity in this process is to combine new information with prior experiences. We investigated the strategy of combining these information sources in color vision. Single cones in human subjects were stimulated and the associated percepts were recorded. Subjects rated each flash for brightness, hue, and saturation. Brightness ratings were proportional to stimulus intensity. Saturation was independent of intensity, but varied between cones. Hue, in contrast, was assigned in a stereotyped manner that was predicted by cone type. These experiments revealed that, near the fovea, long and middle wavelength sensitive cones produce sensations that can be reliably distinguished on the basis of hue, but not saturation or brightness. Taken together, these observations implicate the high-resolution, color-opponent parvocellular pathway in this low-level visual task.

Reconciling Color Vision Models With Midget Ganglion Cell Receptive Fields

“…The responses are highly consistent and reflect activity in the midget RGCs with single cone centers (Schmidt et al, 2019). Consistent with parallel processing of hue and spatial information by separate types of midget RGCs, stimulation of most L/M-cones in the central retina results in percepts of white, with only a small subset eliciting color percepts (Figure 3B; Sabesan et al, 2016; Schmidt et al, 2018a, b). Further, the homogeneity of the surrounding cone type had no effect on which cones were associated with a perceived color, arguing against the idea that midget RGCs with strong L vs. M opponency serve hue perception.…”

Diverse Cell Types, Circuits, and Mechanisms for Color Vision in the Vertebrate Retina

“…However, if output from a subset of cones was reserved exclusively for chromatic vision, this would degrade achromatic acuity and, as mentioned above, acuity at the foveal center closely follows the Nyquist limit predicted from cone-to-cone spacing (391). An alternate idea is that the brain might learn a map of the cone mosaic through experience (26,396). While the likelihood of reporting green or red following single cone stimulation was not significantly enhanced in cones that were immediately surrounded by cones of a different spectral sensitivity (393), the threshold for single cone detection of a colored light stimulus was elevated by use of an adapting light of the opposite color when the cone was surrounded by cones of the opposite spectral sensitivity (453).…”

It’s not easy seeing green: the veridical perception of small spots

“…Does it matter if this is achieved through increasing the stimulus size, or by allowing a small stimulus to move across the retina? And finally, while previous research has shown that varying the intensity of single-cone stimuli does not affect hue perception (Schmidt et al, 2018), does it have an effect for larger stimuli?…”

“…Previous studies have examined the repeatability of hue judgments for stimuli delivered to individual cones and pairs of cones (Sabesan et al, 2016; Schmidt et al, 2018; Schmidt et al, 2019). In the current study, a different group of 6-7 target locations centered on cones were chosen on each session.…”

“…More recent studies used image-based eye tracking (Arathorn et al, 2007; Harmening, Tuten, Roorda, & Sincich, 2014; Yang, Arathorn, Tiruveedhula, Vogel, & Roorda, 2010) in an adaptive optics scanning laser ophthalmoscope (AOSLO) system to accurately target and deliver stimuli to single cones and investigate the percepts elicited thereby. Presenting 543-nm stimuli on a white background that equated the baseline adaptive state of the three cone types in eyes whose cone mosaics had been mapped, Sabesan, Schmidt, Tuten, and Roorda (2016) and Schmidt, Boehm, Foote, and Roorda (2018) showed that the spectral identity of each cone is recapitulated in its color percepts. While many stimuli appeared white, monochromatic light delivered to L cones was more likely to appear red, and the same light delivered to M cones was more likely to appear green.…”